Submission #20156

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
20156	2016-02-28T16:50:15 Z	tonyjjw	괄호 (kriii4_R)	C++14	100 / 100	354 ms	16708 KB

R

//*
#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<algorithm>
#include<vector>
#define all(A) (A).begin(), (A).end()
   
using namespace std;
   
typedef long long ll;
typedef pair<int,int> pii;
   
const int MN = 1000000+10;
const ll mod = 1000000007;
   
ll fact[MN];
ll inv[MN];
   
ll pow(ll a,ll p){
    ll r=1;
    while(p>0){
        if(p&1)r=r*a%mod;
        a=a*a%mod;
        p>>=1;
    }
    return r;
}
   
ll comb(ll n,ll r){
    return fact[n]*inv[r]%mod*inv[n-r]%mod;
}
ll inverse(ll a){
    return pow(a,mod-2);
}
   
int main(){
    int N,K;
    scanf("%d%d",&N,&K);
    fact[0]=1;
    for(int i=1;i<MN;i++){
        fact[i]=fact[i-1]*i%mod;
    }
    for(int i=0;i<MN;i++){
        inv[i]=inverse(fact[i]);
    }
    ll ans=0;
    for(int i=0;2*i<=N;i++){
        ll v;
        if(i==0){
            v=1;
        }
        else{
            v=comb(N,i)-comb(N,i-1);
        }
        v*=pow((ll)K,(ll)N-i);
        v%=mod;
        ans+=v;
        ans%=mod;
    }
    if(ans<0)ans+=mod;
    printf("%lld\n",ans);
    return 0;
}
//*/

Subtask #1

8.0 / 8.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	281 ms	16708 KB	Output is correct
2	Correct	263 ms	16708 KB	Output is correct
3	Correct	327 ms	16708 KB	Output is correct
4	Correct	328 ms	16708 KB	Output is correct
5	Correct	337 ms	16708 KB	Output is correct
6	Correct	296 ms	16708 KB	Output is correct
7	Correct	298 ms	16708 KB	Output is correct
8	Correct	289 ms	16708 KB	Output is correct
9	Correct	270 ms	16708 KB	Output is correct
10	Correct	257 ms	16708 KB	Output is correct
11	Correct	257 ms	16708 KB	Output is correct
12	Correct	320 ms	16708 KB	Output is correct
13	Correct	325 ms	16708 KB	Output is correct
14	Correct	282 ms	16708 KB	Output is correct
15	Correct	288 ms	16708 KB	Output is correct
16	Correct	277 ms	16708 KB	Output is correct
17	Correct	345 ms	16708 KB	Output is correct
18	Correct	348 ms	16708 KB	Output is correct
19	Correct	350 ms	16708 KB	Output is correct
20	Correct	346 ms	16708 KB	Output is correct

Subtask #2

92.0 / 92.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	278 ms	16708 KB	Output is correct
2	Correct	265 ms	16708 KB	Output is correct
3	Correct	266 ms	16708 KB	Output is correct
4	Correct	336 ms	16708 KB	Output is correct
5	Correct	310 ms	16708 KB	Output is correct
6	Correct	323 ms	16708 KB	Output is correct
7	Correct	298 ms	16708 KB	Output is correct
8	Correct	279 ms	16708 KB	Output is correct
9	Correct	295 ms	16708 KB	Output is correct
10	Correct	260 ms	16708 KB	Output is correct
11	Correct	332 ms	16708 KB	Output is correct
12	Correct	329 ms	16708 KB	Output is correct
13	Correct	328 ms	16708 KB	Output is correct
14	Correct	291 ms	16708 KB	Output is correct
15	Correct	299 ms	16708 KB	Output is correct
16	Correct	300 ms	16708 KB	Output is correct
17	Correct	261 ms	16708 KB	Output is correct
18	Correct	353 ms	16708 KB	Output is correct
19	Correct	353 ms	16708 KB	Output is correct
20	Correct	354 ms	16708 KB	Output is correct